What Is Quantum Computing?

Quantum Computing in One Paragraph

Quantum computing is a fundamentally different way of processing information. Instead of using bits (0s and 1s) like a normal computer, a quantum computer uses qubits — which can exist in multiple states at once thanks to a property called superposition. This allows quantum computers to explore many possibilities simultaneously, potentially solving certain problems exponentially faster than the best supercomputers on Earth.

Why It Matters

Quantum computers aren't just faster versions of your laptop. They work on entirely different principles, which means they're suited to entirely different types of problems — problems that would take classical computers millions or billions of years to solve.

• Drug discovery — simulating molecular interactions at the quantum level, potentially finding new medicines in days rather than decades
• Cryptography — a sufficiently powerful quantum computer could break today's encryption, which is why governments and banks are paying close attention
• Materials science — designing new batteries, superconductors and catalysts by simulating atomic behaviour directly
• Optimisation — solving complex logistics, supply chain and financial modelling problems with vast numbers of variables
• AI and machine learning — quantum-enhanced training could accelerate AI development significantly

Key Concepts to Understand

You don't need a physics degree to grasp the basics. Here are the three ideas that matter:

• Qubits — the basic unit of quantum information. Unlike a classical bit (0 or 1), a qubit can be in a superposition of both states at once.
• Superposition — the ability of a quantum system to exist in multiple states simultaneously until measured. Think of a spinning coin — it's not heads or tails until it lands.
• Entanglement — when two qubits become linked so that the state of one instantly affects the other, even at vast distances. Einstein called it "spooky action at a distance."

Who's Building Quantum Computers?

The field includes some of the world's largest tech companies and several ambitious pure-plays:

• IBM — the longstanding leader, with over 1,000 qubit processors and a public quantum cloud platform
• Alphabet (Google) — claimed "quantum supremacy" in 2019 and continues to advance its error-corrected architecture
• Microsoft — pursuing a unique "topological qubit" approach that could be more stable than rivals
• IonQ — a public pure-play using trapped-ion technology, backed by Amazon and Samsung
• Rigetti Computing — a public pure-play using superconducting qubits
• D-Wave Quantum — the first commercial quantum computing company, using quantum annealing for optimisation problems
• Quantinuum (Honeywell) — formed by the merger of Honeywell Quantum Solutions and Cambridge Quantum, with strong UK ties

The UK Angle

The UK is a significant player in quantum computing. The UK National Quantum Strategy commits £2.5 billion to quantum technologies over ten years (2024–2034). British universities including Oxford, Cambridge and Bristol are at the forefront of quantum research, and companies like Quantinuum have major operations in the UK. For British investors, this means quantum computing isn't just a distant Silicon Valley story — it's happening closer to home.

Why Invest in Quantum Computing?

The investment case is straightforward: quantum computing could become a massive market — some estimates suggest $1 trillion+ in value creation over the next two decades. The companies that establish dominance early could reap enormous rewards, similar to how early leaders in AI (Nvidia, Microsoft) have dominated that wave.

However, it's important to be realistic. Most pure-play quantum companies are pre-profit, with revenues in the single-digit millions. The technology is still early-stage, and it may be years before quantum computing generates meaningful commercial returns. This is a long-term, high-risk investment thesis.

The Bottom Line

Quantum computing is a revolutionary technology that uses the principles of quantum mechanics to solve problems beyond the reach of classical computers. It's still early days, but the potential is enormous — and for investors willing to accept the risks, there are multiple ways to gain exposure from the UK.

Next Steps

• How Quantum Computers Work — the physics in more detail
• Top Quantum Computing Stocks — the companies to know
• How to Buy Quantum Stocks in the UK — the practical guide

Nothing on this site is financial advice. All content is educational. Always do your own research and consult a qualified financial adviser before making investment decisions. Back to all guides.